(Originais Teachy 2024) - Question Hard of Chemistry

It is known that acetone is a type of ketone widely used as a solvent in the industry, mainly for the production of plastics, paints, and varnishes. Furthermore, studies show that its use can pose risks to human health and the environment. Considering the context, answer: a) Describe the general structure of a ketone and what sets it apart from other functional groups. b) Identify and explain some of the risks associated with exposure to acetone for health and the environment. c) Propose individual and collective measures that can be adopted to reduce the negative impacts caused by the responsible use and disposal of acetone.

One of the most fascinating aspects of Chemistry is the ability to transform and exist in different states of aggregation, depending on temperature and pressure conditions. The phase diagram is a powerful tool that helps us visualize and understand these transitions. Consider a system with a pure substance that can exist in the solid, liquid, and gaseous states. Based on the provided phase diagram, answer the following questions: 1) Identify the triple point and explain its importance in the study of phase equilibria. 2) Describe the anomalous behavior of water based on its phase diagram and discuss the biological and environmental implications of this phenomenon. 3) Select a point on the diagram and justify, based on the phase equilibrium lines, in which state the substance would be if subjected to those temperature and pressure conditions.

The German chemist Friedrich August Kekulé was very important for the development of organic chemistry by presenting his postulates on the structure of organic compounds in the 19th century. One of his most important postulates is the tetravalence of carbon. Considering the concept of tetravalence and covalent bonds in organic molecules, answer the following questions: a) Explain why carbon is tetravalent, and briefly describe the relationship of this concept with covalent bonds. b) Give examples of three organic compounds that have tetravalent carbon and their respective structural formulas. c) Describe how the postulate of carbon tetravalence was fundamental for understanding the structures of organic compounds in Kekulé's time and, consequently, how it influenced organic chemistry in general.